Bug in split transactions on Raspberry Pi

Noralf Trønnes noralf at tronnes.org
Tue Jan 26 03:31:36 PST 2016

Den 25.01.2016 23:07, skrev Stefan Wahren:
>> Doug Anderson <dianders at chromium.org> hat am 25. Januar 2016 um 21:44
>> geschrieben:
>> Hi,
>> On Mon, Jan 25, 2016 at 12:05 PM, Alan Stern <stern at rowland.harvard.edu>
>> wrote:
>>> On Fri, 22 Jan 2016, Doug Anderson wrote:
>>>>> Can you tell me how to configure a mainline kernel to work on the
>>>>> Raspberry Pi? There is no arch/arm/configs/bcmrpi_defconfig.
>>>> Not offhand. Again, perhaps someone else on this thread will have
>>>> more. I did do a quick Google search and came up with:
>>>> http://elinux.org/RPi_Upstream_Kernel_Compilation
>>>> ...but the Raspberry Pi I have at home is running some home automation
>>>> stuff so I don't want to give that a try. :-P
>>> I followed those instructions, and the result doesn't boot. No easy
>>> way to figure out why -- nothing shows up on the HDMI screen but the
>>> color splash.
>> Interestingly enough Stefan Wahren reached out to me after my recent
>> patch series indicating that my series didn't fix some other problem
>> he was having on his Raspberry Pi. Presumably that means he might
>> have some pointers?
>> Stefan: do you have any pointer to instructions that Alan can use to
>> get a booting Raspberry Pi kernel based on mainline Linux?
> It sounds like that bootloader doesn't came up.
> You will need to add / replace the following files in the FAT partition of an
> raspbian:
> kernel.img (U-Boot)
> boot.scr.uimg
> bcm2835-rpi*.dtb (from kernel)
> zImage
>> ...another interesting idea would be to try to see if you could just
>> change the configuration of the Raspberry Pi kernel to switch which
>> dwc2 driver it used. Presumably their driver was an addition on top
>> of the driver in "drivers/usb/dwc2". In fact, doing a 'git log' on
>> drivers/usb/dwc2 in the "rpi-4.4.y" kernel on github it looks pure
>> (and Stefan is even the last commit author!)
>> -Doug
> dwc2 is broken in Linux 4.4 and newer

We are using dwc2 downstream[1] on 4.4 to get gadget support on
Pi Zero. I didn't add any extra patches to get that working.
The only difference I can think of is that we boot directly from the
firmware bootloader and turn on USB power in the firmware driver.

I have seen strange dwc2 probing errors when USB power is off.


[1] https://github.com/raspberrypi/linux/tree/rpi-4.4.y

> Please apply the following patch series:
> http://marc.info/?l=linux-usb&m=145255851516121&w=2
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